Links in platform apps should open in the system default browser.

chrome/browser/ui/extensions/shell_window.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_EXTENSIONS_SHELL_WINDOW_H_
 #define CHROME_BROWSER_UI_EXTENSIONS_SHELL_WINDOW_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/extensions/extension_function_dispatcher.h"
 #include "chrome/browser/extensions/extension_keybinding_registry.h"
@@ skipping 79 matching lines @@
   // is on startup and from within UpdateWindowTitle().
   virtual string16 GetTitle() const;
 
   // Call to notify ShellRegistry and delete the window. Subclasses should
   // invoke this method instead of using "delete this".
   void OnNativeClose();
 
   // Save the window position in the prefs.
   virtual void SaveWindowPosition();
 
+  // Set the WebContentsDelegate for external url in test.
+  static void SetExternalUrlControllerForTesting(
+      content::WebContentsDelegate* controller);
+
  protected:
   ShellWindow(Profile* profile,
               const extensions::Extension* extension);
   virtual ~ShellWindow();
 
  private:
   // PlatformAppBrowserTest needs access to web_contents()
   friend class extensions::PlatformAppBrowserTest;
 
   // Instantiates a platform-specific ShellWindow subclass (one implementation
@@ skipping 90 matching lines @@
 
   // Used for loading app_icon_.
   scoped_ptr<ImageLoadingTracker> app_icon_loader_;
 
   scoped_ptr<NativeShellWindow> native_window_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellWindow);
 };
 
 #endif  // CHROME_BROWSER_UI_EXTENSIONS_SHELL_WINDOW_H_